/**
 * 获取DPI
 * @returns {Array}
 */
function conversion_getDPI() {
  var arrDPI = new Array
  if (window.screen.deviceXDPI) {
    arrDPI[0] = window.screen.deviceXDPI
    arrDPI[1] = window.screen.deviceYDPI
  } else {
    var tmpNode = document.createElement('DIV')
    tmpNode.style.cssText = 'width:1in;height:1in;position:absolute;left:0px;top:0px;z-index:99;visibility:hidden'
    document.body.appendChild(tmpNode)
    arrDPI[0] = parseInt(tmpNode.offsetWidth)
    arrDPI[1] = parseInt(tmpNode.offsetHeight)
    tmpNode.parentNode.removeChild(tmpNode)
  }
  return arrDPI
}

/**
 * px转换为mm
 * @param value
 * @returns {number}
 */
const pxConversionMm = function(value) {
  var inch = value / conversion_getDPI()[0]
  var c_value = inch * 25.4
//      console.log(c_value);
  return c_value
}
/**
 * mm转换为px
 * @param value
 * @returns {number}
 */
const mmConversionPx = function(value) {
  var inch = value / 25.4
  var c_value = inch * conversion_getDPI()[0]
//      console.log(c_value);
  return c_value
}

export default {
  pxConversionMm, mmConversionPx
}
//调用直接 new unitConversion().pxConversionMm(像素)
//        new unitConversion().mmConversionPx (毫米)
